Only about half of all students who enroll in colleges and universities in the United States earn a four-year degree at the institution where they begin their studies, and many postsecondary institutions are seeking ways to increase the graduation rates of their students. Both student characteristics and institutional factors influence a student's likelihood of graduating, so it is important for colleges and universities to determine which institutional practices have a significant impact on degree completion. In this longitudinal, ex post facto study, a cohort of 3,458 undergraduate students who matriculated in 2005 at a large, urban public research university in the Mid-Atlantic region of the United States were followed for six years to explore the differences between students who took service-learning courses while enrolled (SL students) and those who did not take service-learning courses (non-SL students). Although SL students and non-SL students had similar pre-college academic characteristics, SL students were more successful while enrolled in college. They earned more credits, had a higher average college GPA, and they graduated at a significantly higher rate than did non-SL students, despite having greater financial need while enrolled. Discrete-time survival analysis showed that service-learning course completion during the third, fourth, and sixth years of enrollment was a significant predictor of graduation for students in this cohort who persisted until the third year. These findings demonstrate that the impact of service-learning on degree completion is substantial, even when traditional predictors for graduation are also considered.